1. Field of the Invention
The present invention relates to an optical switch, a light emitter switching method, a light receiver switching method, a multiplexer, a demultiplexer, and an optical communication system which are used in optical communications and the like.
2. Related Background Art
FIG. 1 shows a typical configuration of a protection system 90 on the demultiplexer side in an optical communication technique. As depicted, the protection system 90 has a configuration in which 2×1 type switches 92 are respectively provided for eight waves of a WDM signal demultiplexed by a demultiplexer 91, whereas 4×1 type switches 93 are disposed at their corresponding output ports. These switches 92, 93 switch from main lines 94 to backup system lines 95. A similar technique is also disclosed in Japanese Patent Application Laid-Open No. 2002-135817
From the viewpoint of optical signals transmitted to the backup system lines 95 in the conventional configuration shown in FIG. 1, two switches 92, 93 are inserted in series, whereby the above-mentioned switching cannot be carried out normally if any of the switches fails. Therefore, the failure probability becomes higher than that in the case where only one switch is inserted.
Also, since the two switches 92, 93 are arranged in series, the number of junctions on transmission lines increases, which enhances transmission loss.
Further, it is difficult for the apparatus to reduce its overall size since the switches 92, 93, which are separate components, are combined together.